Bryant 394GAD blower/switch problem???

______________________________________________________________________ I own a Bryant 394GAD. When I turn on the furnace the gas turns on heats up the heat exchanger, but the blower never comes on. The limit switch reaches it limit and trips the gas off and the blower on. They never work together. I have replaced the control board that was in the furnace with HH84AA020. Which I believe is the wrong board or I need to cut a resister for the relay to the blower??? I think that I should have gotten the ICM271C FAN BLOWER Circuit CONTROL BOARD. Please HELP!!! What do I do??? I just bought this house and have no idea about Furnaces… Jeff Replies: bobzac “Re(1):Bryant 394GAD blower/switch problem???” , posted Mon 11 Dec 17:25 ______________________________________________________________________ Jeff, I had the exact same problem with my 20year old 394GAD. I found that the limit switch (the thing with 2 terminals that screws into the heating chamber) must be closed, for the burners to lightoff. It is closed when cold and opens when the heat box gets too hot, which starts the blower. the red wire has a “microtemp” sensor where it clips onto the limit switch. It kinda looks like a diode. I suspect mine is bad. Anyway, when I bypass that sensor, and turn the thermostat up, the burners light off – but the blower won’t come on in “automatic mode”,because that limit switch must be “open” to make blower kick on. So, as a temporary fix, I only use “on” mode for the blower when using heat. I removed that diode-looking thing, and clipped that red wire directly onto the limit switch terminal. AND keep the blower in “ON” mode when using the heat. So now my furnace works just fine, cycling on and off as the house warms and cools, but the blower runs constantly. I don’t know where to get a new microtemp sensor as I don’t have an owner’s manual, and don’t know what part number it is. I’m not 100% sure that the microtemp sensor is my problem, but it sure appears that’s the case. Since this furnace is installed in an addition, and my main unit adequately heats the addition except on very cold (below 25F) days, I’m not desperate to fix it properly. I also have a good wood stove in the main house which really helps on very cold days. Incidentaly, the blower still works properly in auto mode when using the AC. Bob Zac Freon “Re(1):Bryant 394GAD blower/switch problem???” , posted Sun 9 Oct 15:03 ______________________________________________________________________ To quote you, “I just bought this house and have no idea about Furnaces”. Possibly calling someone who does know about furnaces would be the best advice. However to help you understand your furnace better when talking with a repair person, read this document: 4h-50-4.pdf Note it’s not identical to your furnace but may be close enough in many respects to give you insight. Page 8 is especially informative. willdree “Re(2):Bryant 394GAD blower/switch problem???” , posted Wed 12 Oct 15:35 ______________________________________________________________________ I had two company’s come out and look at it and they both said the control board was the problem. I did some research and found the HH84AA020 control board, bought it and replaced it. But no change at all. I also found in my research a control board model # ICM271, do you think that this could be the problem? What about jumping the g1 to the g3? Jeff